How does Multi-threading render support work in Carrara?

The render engine in Carrara normally uses a multi-threaded render. That is, if the hardware supports multiple threading in the processor(s), then Carrara will use them.

However, if a scene incorporates 'Indirect Lighting,' Then Carrara will perform a first pass before starting the main render. During this time of the first pass, the progress bar will report "Precalculating Lighting." During this period of time, it is *not* multi-threaded. Once this first pass for Indirect Lighting concludes, the main render will begin and will be multi-threaded.